A critical issue for scaled logic devices is the ability to operate with reduced power supply voltages, both in order to reduce power dissipation and in order to mitigate high electric field related problems. The subthreshold swing of present metal oxide semiconductor (MOS) devices (at best 60 mV/decade), and the resultant leakage current, is a major impediment to further scaling of power supply voltage.
Some proposed low subthreshold swing devices are based on tunneling MOSFETs, including structures based on Si and others based on carbon nanotubes. Mosfets based on nanowires and related geometries have also been discussed. See, e.g., P.-F. Wang, et al, “Complementary Tunneling Transistor for Low Power Application,” Solid-State Electronics, 48, 2281 (2004); J. Appenzeller et al, “Comparing Carbon Nanotube Transistors—The Ideal Choice: A Novel Tunneling Device Design.” IEEE Trans. Electr. Dev. 52, 2568 (2005). Interband tunneling devices with GaSb and InAs and related materials have also been used, particularly for resonant tunnel diodes (RTDs). Yu, et al, “Demonstration of Resonant Transmission in InAs/GaSb/InAs Interband Tunneling Devices,” Appl. Phys. Lett. 57, 2677 (1990).